As I see it, a so-called 'folksinger' really should appreciate that very old, traditional, songs shed a light into life long ago that history books can never teach and which would otherwise be totally lost. It's in the atmosphere and in the language. They reflect their time, place and reality. They shouldn't be retrospectively condemned by someone 400 years later. Frankly, I'm amazed that MacColl's political and social prejudices took him that far.
MacColl, a convinced communist, which, given his background, I can respect, definitely had prejudices about the 'aristocracy' - but to take it back to 1571 is I feel is a bit extreme.